When people find out I’m an executive coach, they often ask who my toughest clients are. Inexperienced leaders? Senior leaders who think they know everything? Leaders who bully and belittle others? Leaders who shirk responsibility?

The answer is none of the above. The hardest leaders to coach are those who won’t reflect — particularly leaders who won’t reflect on themselves.

At its simplest, reflection is about careful thought. But the kind of reflection that is really valuable to leaders is more nuanced than that. The most useful reflection involves the conscious consideration and analysis of beliefs and actions for the purpose of learning. Reflection gives the brain an opportunity to pause amidst the chaos, untangle and sort through observations and experiences, consider multiple possible interpretations, and create meaning. This meaning becomes learning, which can then inform future mindsets and actions. For leaders, this “meaning making” is crucial to their ongoing growth and development.

Research by Giada Di Stefano, Francesca Gino, Gary Pisano, and Bradley Staats in call centers demonstrated that employees who spent 15 minutes at the end of the day reflecting about lessons learned performed 23% better after 10 days than those who did not reflect. A study of UK commuters found a similar result when those who were prompted to use their commute to think about and plan for their day were happier, more productive, and less burned out than people who didn’t.

So, if reflection is so helpful, why don’t many leaders do it? Leaders often:

Don’t understand the process. Many leaders don’t know how to reflect. One executive I work with, Ken, shared recently that he had yet again not met his commitment to spend an hour on Sunday mornings reflecting. To help him get over this barrier, I suggested he take the next 30 minutes of our two-hour session and just quietly reflect and then we’d debrief it. After five minutes of silence, he said, “I guess I don’t really know what you want me to do. Maybe that’s why I haven’t been doing it.”

Don’t like the process. Reflection requires leaders to do a number of things they typically don’t like to do: slow down, adopt a mindset of not knowing and curiosity, tolerate messiness and inefficiency, and take personal responsibility. The process can lead to valuable insights and even breakthroughs — and it can also lead to feelings of discomfort, vulnerability, defensiveness, and irritation.

Don’t like the results. When a leader takes time to reflect, she typically sees ways she was effective as well as things she could have done better. Most leaders quickly dismiss the noted strengths and dislike the noted weaknesses. Some become so defensive in the process that they don’t learn anything, so the results are not helpful.

Have a bias towards action. Like soccer goalies, many leaders have a bias toward action. A study of professional soccer goalies defending penalty kicks found that goalies who stay in the center of the goal, instead of lunging left or right, have a 33% chance of stopping the goal, and yet these goalies only stay in the center 6% of the time. The goalies just feel better when they “do something.” The same is true of many leaders. Reflection can feel like staying in the center of the goal and missing the action.

Can’t see a good ROI. From early roles, leaders are taught to invest where they can generate a positive ROI — results that indicate the contribution of time, talent or money paid off. Sometimes it’s hard to see an immediate ROI on reflection — particularly when compared with other uses of a leader’s time.

If you have found yourself making these same excuses, you can become more reflective by practicing a few simple steps.

Identify some important questions. But don’t answer them yet. Here are some possibilities:

What are you avoiding?

How are you helping your colleagues achieve their goals?

How are you not helping or even hindering their progress?

How might you be contributing to your least enjoyable relationship at work?

How could you have been more effective in a recent meeting?

Select a reflection process that matches your preferences. Many people reflect through writing in a journal. If that sounds terrible but talking with a colleague sounds better, consider that. As long as you’re reflecting and not just chatting about the latest sporting event or complaining about a colleague, your approach is up to you. You can sit, walk, bike, or stand, alone or with a partner, writing, talking, or thinking

Schedule time. Most leaders are driven by their calendars. So, schedule your reflection time and then commit to keep it. And if you find yourself trying to skip it or avoid it, reflect on that!

Start small. If an hour of reflection seems like too much, try 10 minutes. Teresa Amabile and her colleagues found that the most significant driver of positive emotions and motivation at work was making progress on the tasks at hand. Set yourself up to make progress, even if it feels small.

Do it. Go back to your list of questions and explore them. Be still. Think. Consider multiple perspectives. Look at the opposite of what you initially believe. Brainstorm. You don’t have to like or agree with all of your thoughts — just think and to examine your thinking.

Ask for help. For most leaders, a lack of desire, time, experience, or skill can get in the way of reflection. Consider working with a colleague, therapist, or coach to help you make the time, listen carefully, be a thought partner, and hold you accountable.

Despite the challenges to reflection, the impact is clear. As Peter Drucker said: “Follow effective action with quiet reflection. From the quiet reflection, will come even more effective action.”

Jennifer Porter is the Managing Partner of The Boda Group, a leadership and team development firm. She is a graduate of Bates College and the Stanford Graduate School of Business, an experienced operations executive, and an executive and team coach.